Circulating estradiol suppresses luteinizing hormone pulse frequency during dietary restriction

Benjamin J. Renquist, Christopher C. Calvert, Betty M. Adams, Thomas E. Adams

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

The influence of dietary restriction on the negative feedback potency of 17-β-estradiol (E2) was evaluated in both castrated male (wethers) and female sheep (OVX ewes) during the breeding season. In study 1, OVX ewes received maintenance or restricted dietary energy for 7 weeks or maintenance energy for 6 weeks prior to a 5 day fast (n = 12 ewes/feeding group). Estradiol (0.31 μg E2/50 kg/h) or vehicle (10% EtOH-saline) was continuously infused into half the animals in each dietary treatment for the final 54 h of the study. The dynamic pattern of LH secretion was assessed during the final 6 h of infusion. Estradiol inhibited luteinizing hormone (LH) pulse amplitude independent of nutrition (P = 0.02); fasting increased mean LH, LH peak height, and LH nadir in the absence of E2 (P = 0.004, P = 0.02, and P = 0.02, respectively); while E2 inhibited pulse frequency (P = 0.02) and increased peak width (P = 0.04) in restricted ewes. Interestingly, despite uniform E2 delivery, serum concentrations of E2 differed with feeding status. Therefore, 12 wethers were infused with 0.31 μg E2/50 kg/h (6 fed, 6 fasted) and six wethers received 0.19 μg E2/50 kg/h (fasted) to establish similar serum concentrations of E2 in fed (0.31 μg/50 kg/h) and fasted (0.19 μg/50 kg/h) wethers. When fed and fasted wethers had uniform serum concentrations of E2 LH pulse frequency was suppressed (P < 0.05) in fasted relative to fed animals, supporting the postulate that energy restriction enhances the E2 negative feedback potency. Collectively, these studies demonstrate that nutrition affects E2 feedback potency and clearance.

Original languageEnglish (US)
Pages (from-to)301-310
Number of pages10
JournalDomestic Animal Endocrinology
Volume34
Issue number3
DOIs
StatePublished - Apr 1 2008
Externally publishedYes

Keywords

  • Clearance
  • Estradiol
  • Luteinizing hormone
  • Nutrition
  • Sheep

ASJC Scopus subject areas

  • Food Animals
  • Animal Science and Zoology
  • Endocrinology

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